Some circuits may be connected to signal sources which may produce signals which have an unreliable magnitude. For example, some signals may fall below a minimum level required to ensure that the circuitry is able to function as expected. Alternatively or additionally, some signals may rise above a maximum allowable level and may result in the circuitry being damaged or destroyed.
Some synchronous circuit designs may require an analog voltage detection signal or Power OK (PWOK) signal to indicate whether a signal is above or below a threshold which is required by the circuitry. The changes to the magnitude of the signal from the signal source may occur asynchronously.